Although particulars vary in many instances, the overall complaint is that people begin to feel nauseated. Just before they are ready to vomit, they sneeze instead. Suddenly, the nausea is gone, and the individual feels fine. Some people have reported that this happens when they first wake up, right after they eat, right before they eat, or arbitrarily during the day. There is no common pattern for the episodes. Some doctors researching this have developed a variety of theories about what may cause the nausea, such as changes in blood pressure, low blood sugar, vertigo, certain types of medication, or changes in sinus pressure. But to date, clinicians have not definitively linked nausea, regardless of its cause, to sneezing, or why sneezing cures the person completely. Presently, there are no active trials or studies to determine the connection, if any exists. One theory above all others has become at least the predominant theory as to how these two body reactions may be tied together. Regardless of the initial cause of the nausea, some doctors now believe that gastritis is the start of the problem. A person develops gastritis for any number of reasons. Gastritis generates stomach acid, which in turn can lead to acid reflux. The acid reflux irritates the Vagus nerve, the central nerve to many of the digestive organs, as well as the throat and mucus membrane. When acid irritates this nerve, it presents the feeling of nausea to the patient. But because the mucus membrane is also irritated, and is the most sensitive of all the organs served by the Vagus nerve, it causes the person to sneeze to relieve the irritation of the Vagus nerve. The person then feels fine. The sneeze also increases chest pressure, which restricts stomach acid and acid reflux. Patients who have this issue are told to minimize their potential for development of gastritis and prevent the problem altogether. Some of the instructions given to patients by their doctors include taking sips of cold water throughout the day and avoiding vitamins or medicines on an empty stomach that may cause gastritis. It is recommended to eat smaller meals than fewer bigger ones, to keep food in the stomach at all times, and eat a couple of dry crackers before getting out of bed in the morning (to minimize the effect of vertigo on nausea), and stay in bed for another half-hour to allow them to absorb excess acid. Also, try to eat solid food first, then wait an hour before drinking any liquids. Avoid greasy foods at all costs. Source
